Both Timberlake and Fallon, who have proven to be oddly-skilled mimics, pulled out on-the-nose impressions of the Doobie Brothers singer. But the performance was absolutely made when McDonald himself showed up.

McDonald is no stranger to self-deprecation, having appeared in a few episodes 30 Rock, so it wasn’t a total surprise when the crooner appeared as the third voice in a heavily harmonized white-funk version of the children’s song.